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SAMPLE INFO : Jensen_2008_Chester_Bluff_Andrew_Creek_tephra
Sample ID:Jensen_2008_Chester_Bluff_Andrew_Creek_tephra
Station ID:Jensen_2008_Chester_Bluff
Latitude:65.38
Longitude:-142.66997
Datum:NAD83
Sample Type 1:Tephra Fall
 Text Description:
Only present at Site A of Chester Bluff. Andrew Creek (AC) tephra is white, up to 0.5 cm thick and continuous over 75 cm at Site A. It is directly above a highly deformed organic-rich horizon and is partially reworked into thinly laminated silt with detrital plant material and rare ripples <1 cm thick. A high percentage of feldspar in AC displays albite twinning. Contaminated by detrital material but also appear to be dominated by green amphibole and some ortho-pyroxene. The composition reported was calculated from analyses of three samples: UA1062, UT1877, and UT1665.

References:
An extensive middle to late Pleistocene tephrochronologic record from east-central Alaska
Tephrochronology of middle to late Pleistocene loess in east-central Alaska

GEOCHEM DATA
StationIDLatitudeLongitudeGeologistDateVisitedAge InfoVolcanoEruptionLocation DescriptionText DescriptionSample IDSample Type 1Sample Type 2Final UnitMaterialCoeffSiO2TiO2Al2O3FeOTMnOMgOCaONa2OK2OP2O5Total-majorsREF majorsMETH majorsFe2O3/Fe203T origFeO/FeOT origVolatiles csvMETH volatilesCsRbBaSrLaCePrNdSmEuGdTbDyHoErTmYbLuYZrNbHfTaPbThUScVCrFeCoNiCuZnGaMoAsNaKRef trace1METH trace1RbBaSrLaCeNdSmEuGdDyErYbLuYZrNbPbThUScTiVCrNiCuZnGaRef trace2METH trace2Light csvHalogen csvother major csvother lile csvother ree csvother hfse csvother hpe csvother tm csvother misc csv
Jensen_2008_Chester_Bluff65.38-142.66997Jensen, B. J. L.< 780000 stratigraphy; 10291; Age based on magnetic polarity of the sediments.Chester Bluff is located in Yukon Charley Rivers National Preserve (YCNP) in east-central Alaska, on the northwest bank of the Yukon River directly upstream from its confluence with the Charley River. It is a terrace comprising a series of individual bluffs dissected by gullies that extend laterally for about 3 km. The south-facing bluffs are dry and substantial excavation (>2m) is needed to reach frozen sediments. Chester Bluff can be broadly differentiated into four units. The base of the bluff is a bedrock terrace exposed up to ~10 m above river level, composed of argillite, part of the Cretaceous Biederman Formation. Deposited on the terrace are 8-10 m of paleo-Yukon River gravel, which are overlain by 5-10 m of sand and silt rhythmites with minor gravel and planar-bedded sand. Up to 40 m of silt, interpreted as loess and interbedded with multiple organic horizons and tephra beds, cap the sequence. Sites A through C were visited in the area and were found to host 19 distinct tephra beds. A near vertical slope at Site A prevented trench completion. Two trenches were excavated on either side of Site A to examine the lateral continuity of tephra beds. Site B was successfully logged from the top of the bluff to the upper-most sand unit associated with the flood deposits. Thick colluvium at Site C prevented completion of the trench at this site. No coordinates provided; location imprecisely georeferenced from Figure 1 in Jensen et al. (2008).Only present at Site A of Chester Bluff. Andrew Creek (AC) tephra is white, up to 0.5 cm thick and continuous over 75 cm at Site A. It is directly above a highly deformed organic-rich horizon and is partially reworked into thinly laminated silt with detrital plant material and rare ripples <1 cm thick. A high percentage of feldspar in AC displays albite twinning. Contaminated by detrital material but also appear to be dominated by green amphibole and some ortho-pyroxene. The composition reported was calculated from analyses of three samples: UA1062, UT1877, and UT1665.Jensen_2008_Chester_Bluff_Andrew_Creek_tephraTephra FallCumulateGlass 77.65 0.17 12.78 1.16 0.05 0.26 1.46 3.62 2.65 6162EMP1.16Cl=0.2; H2O=6.33EMP

SAMPLE LOCATION

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